In an electronic printer, where toner particles are deposited on a surface in image form and are subsequently transferred to a receiving material, such as paper, the toner particles must be fixed onto the receiving material in order to render the images permanent. This fixing process is often achieved by a combination of heat and pressure applied in a fixing nip. For example, the receiving material onto which unfixed toner particles have already been deposited, is passed through the fixing nip where an increased temperature and pressure serve to fix the image permanently to the receiving material. Alternatively, a transfer surface carrying the unfixed toner particles is fed through the fixing nip together with the receiving material, whereby the increased temperature and pressure cause the transfer of the toner particles from the transfer surface to the receiving material and the simultaneous fixing of the toner image thereon.
In such devices, especially where the receiving material is formed of paper or a like fibrous material, debris in the form of dust and fibers can build up in the region of the fixing nip. If this debris remains, the quality of fixing, and the efficiency of the image transfer where applicable, can be affected.
A fixing device is known, for example from European patent specification EP 149860 (Oce-Nederland BV) for fixing toner images onto a receiving material. The device comprises a fixing roller urged into contact with a pressure roller to form a fixing nip therebetween through which a copy sheet passes. A perforated cleaning roller is in contact with the surface of the fixing roller to remove debris therefrom. Toner particles are applied to the cleaning member to render the surface tacky.
In a fixing device described in United States patent U.S. Pat. No. 4,018,555 (Thettu/Xerox Corporation), a fuser roll is urged into contact with a backup roll to form a fixing nip therebetween through which copy paper or substrate material passes. An internally heated cleaning roll having a tacky surface is positioned in contact with the surface of the fixing roll to remove debris therefrom. The cleaning roll can be rejuvenated by the application thereto of a tacky polymeric adhesive.
U.S. Pat. No. 4,705,388 (Huntjens et al/Oce-Nederland BV) describes a method and device for determining the moment that a layer of tacky material on an internally heated cleaning roll needs to be rejuvenated.
We have found that the above mentioned fixing devices are not as successful at removing debris from the fixing nip as may be desired for high quality work. Thus it is an objective of the present invention to provide a device and method in which an improved removal of debris is possible.